Polymeric products and preparation of same



Patented Apr. 16, 1946 OFFICE POLYMERIC PRODUCTS AND PREPARATION OF SAME I Robert R. Dreisbach, Midland, Mich., assignor to,

The Dow Chemical Company, Midland, Mich., a corporation of Michigan in Drawing. Application March 4, 1944, Serial No. 525,092 r 8 Claims. (Cl. 260-74) This invention-concerns certain new thermoplastic copolymers composed for the most part of styrene, but having mechanical properties su perior to those of polystyrene which has been prepared under similar polymerization conditions. The new copolymers are prepared by polymerizing styrene together with from 0.03 to 5.0 and preferably from 0.08 to 1.5 per cent by weight of one or more nuclear halogenated styrenes. The copolymers are clear, transparent, colorless thermoplastic solids which maybe molded, extruded, or machined to obtain finished articles of desired size and shape. They possess excellent dielectric properties and are useful as electric insulating agents. They have a luster and a generalappearance similar to that of the usual solid form of polystyrene. resist distortion under a transversely applied load at temperatures higher than does polystyrene which has been prepared in a similar manner, and'they are superior to the polystyrene in one -or more other mechanical properties such as imifaact strength, tensile strength, hardness, i. e. reentence to scratching, etc. Accordingly, the new copolymers arebetter adapted for many purposes "hair 'is polystyrene;

TheQinventiOn is based upon a discovery that byadmixing a small amount of a nuclear halogenated styrene with styrene prior to polymerizing the latter, products may be obtained having a higher heat-distortion. temperature and improved mechanical properties over those obtained by polymerizing styrene alone under like conditions. ing such improved properties, without the need for employing a considerable proportion of the halogenated styrene as a starting material, it is important'that the polymerizationmixture contain not more than per cent by weight of halogenated styrene, based on the combined weight of the styrene and the nuclear halogenated styrene.

In general, the heat distortion temperature becomes lower and the mechanical properties of the copolymer products become poorer as the proportion of nuclear halogenated styrene chemically combined therein is decreased from 0.03 per cent to zero, or is increased above 5 per cent, e. g. from 5 up to 15 per cent by weight. 'Within the limits of from 0.03 to 5 per cent of the nuclear However, inmost instances they at higher temperatures than does polystyrene pre- However, in order to obtain products havpared under similar polymerizing conditions when they contain in chemically combined form from 0.03 to 1.5 per cent of the nuclear halogenated styrene.

By employing a considerable proportion, e. g. 15 per cent by weight or more, of a halogenated styrene in the mixture 01' polymerizable compounds, products may in some instances be produced having heat distortion temperatures'and mechanical properties as good as those of the products prepared from the mixture containing 5 per cent by weight or less of the halogenated styrene. However, the nuclear halogenated styrenes are more expensive and dimcult to prepare than is styrene; hence, the employment of such considerable proportion of a halogenated styrene is disadvantageous. a

The copolymeric products are prepared by adding one or more nuclear halogenated'styrenes, such as monochiorostyrene, monobromostyrene,

dichlorostyrene or dibromostyrene, etc., to styrene in amount such as to form a mixture containing from 0.03 to 5 per cent, and usually from 0.03 to 1.5 per cent, of the halogenated styrene, based on the combined weight of the polymerizable same or by exposure to actinic light, or by formhalogenated compound in the coplymer product, I

the optimum proportion varies somewhat depending upon the particular nuclear halogenated styrene employed. For instance, copolymers of ing an aqueous emulsionof the polymerizable compounds and polymerizing the latterwhile in tures of from to 0., to effect the po1ymerization. Polymerization en masse may, if desired, be carried out within a mold so as to obtain directly a, finished article of desired size and shape. The product may, if desired, be molded,

4 slum to form the Gri gnard reagent, reacting said extruded, or machined to produce finished articles in the waysusual with polystyrene. Articles prepared from the product are superior to polystyrene in at least one, and usuall several, mechanical properties such as tensile strength, impact strength, resistance to scratching of the surface, and resistance to distortion by an appliedforceat temperatures higher than those at which polystyrene resists distortion. 4

The following examples illustrate certain ways in which the principle of the invention has been applied, but are not to be construed as limiting the invention. i

EXAMPLE '1 In each of a series of experiments, para-chlorostyrene was admixed with styrene in the propo'r tlons indicated in the following table and the mixaaeavse agent with ethylene oxide to form dichlorophenylethyl alcohol, and dehydrating the alcohol. The dichlorostyrene was added in varying amounts to diflerent samples of styrene. The resultant, 5 mixtures were polymerized by heating the same in closed containers at 125 C. for 3 days. Each p lymerized, product was molded into test pieces,

l and the latter were employed in determining the mechanical properties of the product, as in Ex- IQ ample l. The following table states the composition of each mixture subjected to polymerization and gives the heat distortion temperature, the tensile strength, the impact strength, and the per cent power factor of each polymer product. Prodnote having compositions outside the range required by the invention are included in the table for purpose f comparison.

"- Table 1:;

n 7 v Tensile Per cent Heat dis- Impact Per cent 'RunNo. dicbloro-- tortion g stren 11, power .etyrene p.,0. in.l s. factor ture was polymerized by heating the same in a closed container at a temperature of 125 C. for threedays. The solid polymeric product was then removed, crushed to form granules of size suitable ucts herein disclosed, provided the compounds for molding and was molded into standard test pieces. The test pieces were used in determining in the usual ways, the tensilestrength in pounds per square inch cross section; the impact strength in inch-pounds of energy applied by a blow to cause breakage; the Shore Scleroscope hardness; the heat distortion temperature in degrees centigrade; and the per cent electric power factor. It maybe mentioned that, except for the size of the test piece, the methods used in determining the impact strength and the heat distortion temperature are similar to those described in A. S. T. M. D 256-34T and A. S. T. M. D 48-33, respectively. The-following table states the per cent by weight of para-chloro-styrene in each mixture subjected to polymerization and gives the foregoing properties of the polymerized product. For purpose of having compositions outside the range comprised by the invention, are included in the table.

Other modes of applying the principle of the invention may be employed instead of those explained, change being made as regards the prod- 40 claim as my invention:

1. A solid thermoplastic copolymer of styrene and a nuclear halogenated styrene having not more than two halogen atoms in the molecule. which copolymer contains in chemically combined form between 0.03 and 5 per cent by weight of the nuclear halogenated styrene.

2. A solid thermoplastic copolymer of styrene and a nuclear halogenated styrene having not more than two halogen atoms in the molecule,

0 which copolymer contains in chemically combined form between 0.03 and 1.5 per cent by weight of the nuclear halogenated styrene.

3. A solid thermoplastic copolymer of styrene and a nuclear chlorinated styrene having not more than two chlorineatoms in the molecule, which copolymer contains in chemically com- Table 'I Heat Tensile R'un Per cent distortion strength Impact Shore No. styrene mom. tem lbs. strength hardness power I styrene 5w iaotor ion 1 0 so 5,400 0.9 79 0.03 99 1 84 6, 600 1- 0 8O 0. 07 95 5 82 6, 100 0. 9 82 0- 035 EXAMPLE 2 bined form between 0.03 m 5 per cent byweight Dichlorost yrene was prepared by brominating ortho-dichloro benzeneto form mono-bromo-dichlorobenzene, reacting the latter with magneofthe nuclear chlorinated styrene. p v 4. A solid thermoplastic cop lymer of styrene and anuclear-chlorinated styren having not 7, more than .two .chlorine atoms in the molecule,

which copolymer contains in chemically com- .blned form between 0.03 and 1.5 per cent by and a mono-chloro-styrene having a single chlorine atom in the aromatic nucleus, which copolymer'contains in chemically combined form between 0.03 and 5jper cent Joy weight of the mono-chloro-styrene. I v A p 6. A solid thermoplastic copolymer of styrene and 5-per cent by weight of para-chioro-styrene.

7. A solid thermoplastic copolymer of styrene and nuclear dichlorinated styrene, which copolymer containsin chemically combined form between'0.03 and 1.5 per cent by weight of the l dichlorc-styrene.

8. A solid thermoplastic copolymer of styrene and nuclear dichlorinated styrene, which'copolymer contains in. chemically combined formbeic tween 0.03 and 0.5 per cent by weight of the and para-chloro styrene, which copolymer contains .in chemically combined form between 0.03 v

dichloro-styrene.

I ROBERT E. DREISBACH. 

